Dental plaque is present to some degree, in the form of a film; i.e., pellicle, on virtually all dental surfaces. It is a by-product of microbial growth, and comprises a dense microbial layer consisting of a mass of microorganisms embedded in a polysaccharide matrix. The microorganisms present in plaque are mainly coccoidal organisms, particularly in early, soft plaque, which, in the mouths of some persons at least, change to filamentous organisms after a few days. Plaque itself adheres firmly to dental surfaces and is removed only with difficulty even through a rigorous brushing regimen. Moreover, plaque rapidly reforms on the tooth surface after it is removed.
A wide variety of microorganisms are found in the oral cavity, and among these are gram-positive anaerobic rods associated with the development of plaque such as Corynebacterium. Nocardia and Neisseria streptococci, such as S. mutans. S. bovis, S. salivarius. Gram-positive streptococci of the genus Peotostreotococcus have also been identified (see, Robert J. Fitzgerald in The Alabama Journal of Medical Sciences. Vol. 5, No. 3, Jul., 1968, pp. 241-242).
The above mentioned microorganisms play a key role in the etiology of plaque. The bacterial organisms associated with plaque formation produce a capsular material which apparently causes the cells of the organism to adhere to each other, holding the plaque together and allowing for further growth. For example, one of the capsule forming bacteria which occurs in large numbers in early plaque is Neisseria sicca. In addition to the aforementioned microorganisms, there is also present in plaque relatively small amounts of other substances such as salivary proteins, carbohydrates, epithelial cells and leukocytes.
Plaque may form on any parts of the tooth surface, and is found particularly at the gingival margin, in cracks in the enamel, and on the surface of the dental calculus. As discussed in greater detail below, the danger associated with the formation of plaque on the teeth lies in the tendency of plaque to build up and eventually produce gingivitis, periodontitis and other types of periodontal disease, as well as dental caries and dental calculus.
More specifically, dental plaque is a precursor to the formation of the hard crystalline buildup on teeth referred to as dental calculus. Both the bacterial and the nonbacterial components of plaque mineralize to form calculus, which comprises mineralized bacteria as well as organic constituents, such as epithelial cells, live bacteria, salivary proteins, leukocytes, and crystals of substances having molecularly bound calcium and phosphorus, e.g., hydroxyapatite, 3Ca.sub.3 (PO.sub.4).sub.2 .multidot.Ca(OH).sub.2, octacalcium phosphate, Ca.sub.8 (HPO.sub.4).sub.2 (PO.sub.4).sub.4 .multidot.5H.sub.2 O, brushite, CaHPO.sub.4 .multidot.2H.sub.2 O, and whitlockite, which is considered to have the form of a beta-Ca.sub.3 (PO.sub.4).sub.2.
Dental plaque and, hence, calculus are particularly prone to form at the gingival margin, i.e., the junction of tho tooth and gingiva. The buildup of plaque at the qingival margin is believed to be the prime cause of gingivitis and other periodontal disorders.
Regular tooth brushing with a conventional dentifrice for some persons greatly retards or even prevents the accumulation of significant amounts of plaque and calculus. For other persons, however, plaque builds up rapidly even with regular brushing which, in turn. leads to the formation of calculus, caries, and presents the danger of periodontal diseases. Removal of plaque and/or calculus by a dentist is currently the only safeguard against serious gingival inflammation caused by the accumulation of significant amounts of plaque in some individuals. It is widely recognized in dentistry that a rigorous brushing regimen alone for many individuals will not prevent the formation of significant amounts of plaque.
Mouthwashes are employed in conventional regimens of oral hygiene. However, conventional mouthwashes serve primarily to sweeten the breath, are formulated for that purpose, and are believed not to function in any significant way to loosen or remove plaque from the dental surfaces. Moreover, since the user typically does not employ a mouthwash expressly for the purpose of cleansing the teeth of plaque, mouthwashes are not routinely used immediately prior to brushing as a way of rendering plaque and/or calculus more amenable to removal during the subsequent brushing process.
Most mouthwashes and pre-rinses contain alcohol and other antimicrobial substances which may alter the critically balanced microflora of the mouth. Generally, these alcohol containing preparations cannot be used on sensitive or irritated gums nor safely by children or those individuals recovering from alcohol abuse. Moreover, the alcohol content in these preparations usually restricts the practical requirement of sufficient contact time in the mouth due to the irritation of the oral mucosa. Most rinse and pre-rinse preparations include instructions advising the consumer to swish the product in the mouth for about 60 seconds. The pain and mucosa irritation due primarily to alcohol astringency is often so intense that most rinse and pre-rinse users actually expectorate in only a few seconds which is usually followed by a water rinse. This relatively short residence time followed by water rinsing dramatically reduces any mouth cleansing and/or plaque fighting effect that these preparations might have.
Most oral rinses sold commercially today contain alcohol in concentrations ranging from between about 5 and about 27% by weight. These high alcohol concentrations impart microbial stability to these rinses. These antiseptic rinses also usually contain other antimicrobial substances such as phenolics, thymol, eucalyptol, cetylpyridinium chloride, sodium benzoate, sanguanarine root, etc., at levels far beyond that required for preservation during storage. The cleaner concentrations generally range from 0.1 to about 0.25%, and generally less than 1.0%. Most rinses make various claims ranging from germ kill, cavity fighting and plaque or tartar control to breath freshening, but few address the critical issue; cleaning the oral cavity.
Various types of commercial oral rinses are employed in diverse regimens of oral hygiene. These include:
a. Conventional mouthwashes which serve primarily to sweeten the breath with volatile flavor odors and are not formulated to function in any significant way to cleanse the mouth of debris and/or to loosen or remove plaque from dental surfaces. PA1 b. Pre-rinse formulations, used immediately prior to brushing as a way of rendering plaque and/or calculus more amenable to removal during the subsequent brushing process. See for example, U.S. Pat. No. 4,657,758, and PA1 c. Gingivitis and/or tartar control rinses containing antimicrobials such as phenols, sanguinaria, chlorhexidine and stannous fluoride; and antitartar or plaque fighters such as sodium or potassium pyrophosphates and sodium benzoate. Some of these are described in the review by K. S. Kornman, Dent. Placue Control Meas. Oral Hyg. Pract. Proc., pp. 121-142 (1986). PA1 a. interfere with the continued swishing action required i.e., up to 60 seconds, PA1 b. does not fill the mouth to an unpleasant level, and PA1 c. does not interfere with effective liquid contact with tooth and mouth surfaces. PA1 a. condition gums and teeth, PA1 b. coat surfaces of the mouth with a lasting, plaque disrupting coating and cleaning mixtures that is ingestible, PA1 c. clear the mouth of debris, PA1 d. impart a lasting smooth, clean, just-brushed feeling to the mouth, PA1 e. are low-foaming and ingestible, PA1 f. disrupt the plaque matrix and control plaque formation without killing germs and/or altering the microflora of the mouth, PA1 g. are particularly effective in conditioning sensitive and irritated gums, and PA1 h. can be safely used as children's rinses; not only because they are alcohol free but also because the cleaner/coating compositions of the invention can be ingested and thus are not harmful if accidentally swallowed by a child.
All of these commercial rinses are characterized by a relatively high alcohol content and antimicrobial and/or antiseptic activity that disrupts the critically balanced microflora of the mouth. This alcohol content also provides the rinse a microbially stable formulation, which does not support the growth of microorganisms, and allows the rinse to be stored for prolonged periods and/or used without concern for microbial contamination. The alcohol also serves to reduce the foamability of the rinse. However, this foaming control is limited to relatively low surfactant concentrations in the rinse. Finally, alcohol also functions as a solvent for the flavor oils typically included in commercial rinses.
There are inherent limitations in the use of alcohol containing oral rinses. For example, most adults will experience some form of gum irritation, on average about once a year. This irritation ranges from sites of early gingivitis, canker sores and trench mouth to periodontal disease. At such times, alcohol rinses cause even greater pain and are often replaced by rinsing with water.
Alcohol containing rinses and/or pre-rinses are generally not used by children. Most parents are concerned about the alcohol content, while many children reject the alcohol bite and astringency characteristic of such products. Indeed, most alcohol containing rinses and/or pre-rinses boldly display the language "Keep Away From Children" on their labels. Similarly large numbers of adults reject alcohol based rinses for various personal reasons. Additionally, recovering alcoholics avoid alcohol rinses because of the threat that these substances can trigger a negative response. For example, most institutionalized personnel are not allowed to use alcohol based rinses.
There is, therefore, a definite need in the art for an oral hygiene composition which is microbially stable, alcohol-free and non-irritating; that can be used as an oral rinse or pre-rinse to clean and condition the teeth and gums, cleanse the mouth of debris and disrupt plaque matrix formation, without substantially altering the microflora balance of the oral cavity.
In view of the foregoing, it is an object of this invention to provide an improved dental rinse which is non-irritating and which has a disruptive cleaning effect upon plaque; which conditions the teeth and gums and which clears the mouth of debris, and disrupts plaque matrix formation, all without altering the balanced microflora of the oral cavity; wherein the rinse is alcohol-free yet microbiologically stable.
It is also an object of this invention to provide an improved method of oral hygiene, i.e., the method of disrupting plaque, clearing the mouth of debris, conditioning teeth and gums without altering the microflora balances of the oral cavity, which entails using the alcohol-free rinse of the present invention.
It is a further object of this invention to provide an improved process for manufacturing an alcohol-free dental rinse.